Comparative study of the chemical composition and biological activities of the essential oils of Senecio gallicus from Tunisia.

The essential oils of flowers and remaining parts of the plant Senecio gallicus (Asteraceae), growing wild in Sfax (Tunisia), were obtained by hydrodistillation over a period of two years (2012 and 2013). Their analysis by Gas Chromatography-Mass Spectrometry (GC-MS), led to a total number of 36 components, belonging to different classes of chemical compounds. Oils compositions were characterized by the abundance of monoterpenes hydrocarbons, the major compounds present in flowers for the two years of study were  respectively the sabinene (49.45% and 28.86%), the α-pinene (9.67% and 9.1%), and the β-myrcene (9.88% and 10.97%). These compounds were also dominant in the essential oils of the plant without flowers where they represent (65.34% and 55%) for the sabinene, (4.14% and 7.3%) for α-pinene, and (6.86% and 0%) for β-myrcene. Obtained essential oils were tested for many biological activities and showed a moderate effect against the fungus Trichoderma reesei and bacteria such as Bacillus sp and Staphylococcus aureus. This study of the Senecio gallicus essential oils represents the first one in Tunisia

Whole and Purified Aqueous Extracts of Nigella sativa L. Seeds Attenuate Apoptosis and the Overproduction of Reactive Oxygen Species Triggered by p53 Over-Expression in the Yeast Saccharomyces cerevisiae

Plants are an important source of pharmacologically active compounds. In the present work, we characterize the impact of black cumin (Nigella sativa L.) aqueous extracts on a yeast model of p53-dependent apoptosis. To this end, the Saccharomyces cerevisiae recombinant strain over-expressing p53 was used. The over-expression of p53 triggers the expression of apoptotic markers: the externalization of phosphatidylserine, mitochondrial defect associated with cytochrome-c release and the induction of DNA strand breaks. These different effects were attenuated by Nigella sativa L. aqueous extracts, whereas these extracts have no effect on the level of p53 expression. Thus, we focus on the anti-apoptotic molecules present in the aqueous extract of Nigella sativa L. These extracts were purified and characterized by complementary chromatographic methods. Specific fluorescent probes were used to determine the effect of the extracts on yeast apoptosis. Yeast cells over-expressing p53 decrease in relative size and have lower mitochondrial content. The decrease in cell size was proportional to the decrease in mitochondrial content and of mitochondrial membrane potential (ΔΨm). These effects were prevented by the purified aqueous fraction obtained by fractionation with different columns, named C4 fraction. Yeast cell death was also characterized by reactive oxygen species (ROS) overproduction. In the presence of the C4 fraction, ROS overproduction was strongly reduced. We also noted that the C4 fraction promotes the cell growth of control yeast cells, which do not express p53, supporting the fact that this purified extract acts on cellular mediators activating cell proliferation independently of p53. Altogether, our data obtained on yeast cells over-expressing p53 demonstrate that anti-apoptotic molecules targeting p53-induced apoptosis associated with mitochondrial dysfunction and ROS overproduction are present in the aqueous extracts of Nigella seeds and in the purified aqueous C4 fraction

Comparative study of the chemical composition and biological activities of the essential oils of Senecio gallicus from Tunisia.

The essential oils of flowers and remaining parts of the plant Senecio gallicus (Asteraceae), growing wild in Sfax (Tunisia), were obtained by hydrodistillation over a period of two years (2012 and 2013). Their analysis by Gas Chromatography-Mass Spectrometry (GC-MS), led to a total number of 36 components, belonging to different classes of chemical compounds. Oils compositions were characterized by the abundance of monoterpenes hydrocarbons, the major compounds present in flowers for the two years of study were  respectively the sabinene (49.45% and 28.86%), the α-pinene (9.67% and 9.1%), and the β-myrcene (9.88% and 10.97%). These compounds were also dominant in the essential oils of the plant without flowers where they represent (65.34% and 55%) for the sabinene, (4.14% and 7.3%) for α-pinene, and (6.86% and 0%) for β-myrcene. Obtained essential oils were tested for many biological activities and showed a moderate effect against the fungus Trichoderma reesei and bacteria such as Bacillus sp and Staphylococcus aureus. This study of the Senecio gallicus essential oils represents the first one in Tunisia

FTIR spectroscopy of whole cells for the monitoring of yeast apoptosis mediated by p53 over-expression and its suppression by Nigella sativa extracts

International audiencep53 over expression in yeast results in cell death with typical markers of apoptosis such as DNA fragmentation and phosphatidylserine externalization. We aimed to substitute/supple-ment classical fluorescent techniques (TUNEL, Annexin V, ROS detection) usually used to detect biochemical changes occurring during yeast apoptosis mediated by p53 over expression and the effect of anti-apoptotic purified molecules from Nigel (Nigella sativa) extracts on these same yeasts by the label free technique of FTIR spectroscopy. The comparison of the entire IR spectra highlighted clear modifications between apoptotic p53-expressing yeasts and normal ones. More precisely, DNA damage was detected by the decrease of band intensities at 1079 and 1048 cm-1. While phosphatidylserine exposure was followed by the increase of νsCH 2 and νasCH 2 bands of unsaturated fatty acids that were exhibited at 2855 and 2926 cm-1 , and the appearance of the C = O ester functional group band at 1740 cm-1. In a second step, this FTIR approach was used to estimate the effect of a purified fraction of the Nigel extract. The modulation of band intensities specific to DNA and membrane status was in agreement with apoptosis supression in presence of the Nigel extracts. FTIR spectroscopy is thus proven to be a very reliable technique to monitor the apoptotic cell death in yeast and to be used as a means of evaluating the biomolecules effect on yeast survival

A Lobularia maritima LmSAP protein modulates gibberellic acid homeostasis via its A20 domain under abiotic stress conditions.

Stress-associated proteins (SAPs) are favorable targets to improve stress tolerance in plants, owing to their roles in developmental processes and stress responses. However, the role of SAPs and the molecular mechanisms by which they regulate plant stress responses remain poorly understood. Previously, it was reported that LmSAP expression was upregulated by various abiotic stressors in Lobularia maritima, and that transgenic tobacco lines with constitutively expressed LmSAPΔA20 and LmSAPΔA20-ΔAN1 showed dwarf phenotypes due to the deficiency of cell elongation under salt and osmotic stresses. In this study, we examined the function of A20 domain in the GA pathway in response to abiotic stresses. Transient expression of acGFP-LmSAPΔA20 and acGFP-LmSAPΔA20-ΔAN1 in onion epidermal cells demonstrated that these fused proteins were localized in the nucleo-cytoplasm. However, the truncated form acGFP-LmSAPΔAN1 was localized in the nucleus. Moreover, comparison of native and truncated LmSAP showed dramatic structural changes caused by the deletion of the A20 domain, leading to loss of function and localization. Interestingly, overexpression LmSAP and truncated LmSAPΔAN1 led to up-regulation of GA biosynthetic genes and increased total gibberellins (GAs) content, corresponding with accelerated development in transgenic tobacco plants. Moreover, the dwarf phenotype of the transgenic lines that express LmSAPΔA20 and LmSAPΔA20-ΔAN1 under stress conditions was fully restored by the application of exogenous GA3. These findings improve our understanding of the role of LmSAP in regulating GA homeostasis, which is important for regulating plant development under abiotic stress conditions

FTIR spectroscopy analysis of the whole recombinant yeast clones W303/pDP and W303/p53.

<p>(a) Dendrogram representing hierarchical cluster analysis of W303/pDP and W303/p53 FTIR spectra. (b) FTIR spectra of W303/pDP (blue line) and W303/p53 (red line) grown on MMGAL, (c) spectral intensity band changes in 3000–2820cm⁻¹ region corresponding to membrane changes and spectral intensity band changes in 1187-945cm^-1 region showing DNA changes (d); the values are means of three independent experiments.</p

Spectral peak assignments.

<p>Spectral peak assignments.</p

Effect of p53 expression on yeast growth of the recombinant yeast clones W303/pDP and W303/p53.

<p>(a) Recombinant yeast clones W303/pDP and W303/p53 growth on solid (MMGLU media serves as a control of cell number) and (b) on liquid media. (c) flow cytometric analysis of the phosphatidylserines externalization by FITC-Annexin V/PI costained W303/pDP and W303/p53.</p

FTIR spectroscopy of whole cells for the monitoring of yeast apoptosis mediated by p53 over-expression and its suppression by <i>Nigella sativa</i> extracts - Fig 4

<p>(a) Growth kinetics of W303/pDP on liquid MMGAL in presence or absence of nigel fraction. (b) FTIR spectra of W303/pDP grown on MMGAL in absence (blue line) and in presence (purple line) of Nigel fraction (c) Hierarchical Cluster Analysis of infrared spectra of W303/pDP obtained from cultures with or without nigel fraction.</p

Effect of purified fraction from Nigel extract on the yeast growth of W303/p53.

<p>(a) Yeast clone W303/p53 growth on solid and (b) on liquid media MMGAL in absence and presence of purified Nigel extract. And (c) northern blot analysis of p53 mRNA level in control cell W303/p53 in inducible condition in absence (1) and in presence of Nigel extract (2).(d) Quantification of the blot.</p